Microsoft Azure Service Bus is a fully managed enterprise integration message broker. 
Service Bus can decouple applications and services. 
Service Bus offers a reliable and secure platform for asynchronous transfer of data and state.
Data is transferred between different applications and services using messages. A message is in binary format and can contain JSON, XML, or just text. 
For more information, see https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messaging-overview